Author(s)

Tatsuya Sato¹, Ikuho Yonezawa¹, Mitsugu Todo², Hiromitsu Takano¹, Kazuo Kaneko¹

¹Department of Orthopaedic Surgery, Juntendo University, Tokyo, Japan.
²Renewable Energy Center, Research Institute for Applied Mechanics, Kyushu University, Kasuga, Japan.

Few biomechanical data exist regarding whether the polyetheretherketone (PEEK) spacer or titanium spacer is better for posterior lumbar interbody fusion (PLIF). This study evaluated the biomechanical influence that these types of spacers with different levels of hardness exert on the vertebra by using finite element analysis including bone strength distribution. To evaluate the risk of spacer subsidence for PLIF, we built a finite element model of the lumbar spine using computed tomography data of osteoporosis patients. Then, we simulated PLIF in L3/4 and built models with the hardness of the interbody spacer set as PEEK and titanium. Bones around the spacer were subjected to different load conditions. Then, fracture elements and some stress states of the two modalities were compared. In both models of PLIF simulation, fracture elements and stress were concentrated in the bones around the spacer. Fracture elements and stress values of the model simulating the PEEK spacer were significantly smaller compared to those of the titanium simulation model. For PLIF of osteoporotic vertebrae, this suggested that the PEEK spacer is in a mechanical environment less susceptible to subsidence caused by microfractures of bone tissue and bone remodeling-related fusion aspects. Therefore, PEEK spacers are bio-mechanically more useful.

Posterior Lumbar Interbody Fusion, Biomechanics, Finite Element Analysis, Cage, Polyetheretherketone, Titanium, Osteoporosis

Sato, T. , Yonezawa, I. , Todo, M. , Takano, H. and Kaneko, K. (2018) Biomechanical Effects of Implant Materials on Posterior Lumbar Interbody Fusion: Comparison of Polyetheretherketone and Titanium Spacers Using Finite Element Analysis and Considering Bone Density. Journal of Biomedical Science and Engineering, 11, 45-59. doi: 10.4236/jbise.2018.114005.